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Completing a 7-unit lower anterior bridge using CAD/CAM scanning equipment requires a variety of detailed steps. Fortunately, today’s modern CAD/CAM systems, such as Sirona’s inLab system, can help speed up and simplify scanning, designing and milling.
The inLab system can assist lab technicians in using their craft skills to the fullest. The complete system is comprised of a series of components that can be used individually or in combination, which helps save technicians save time, gain flexibility and safeguard the future of their dental laboratories.
The inLab system is capable of completing all digitization tasks in the dental laboratory. It combines a very short, highly precise measurement, along with operating flexibility and a variety of functions.
The patient wanted to replace a lower partial involving the front four lower anterior teeth to a 7-unit fixed bridge.
01 Using the inLab system’s biocopy feature with anatomic connectors, a bridge is selected for the case.
03 The case is ready to be scanned with the initial diagnostic waxup on Sirona’s inEos X5 scanner’s robotic arm (Fig. 1).
04 After scanning the waxup for biocopy and scanning the working model, the individual dies are scanned for more accuracy in finding the margins (Fig. 2).
Check out this video with images of the case presentation ...
05 The working model and the biocopy waxup are stitched together by the software. The transfer jig is used to aid in stitching two separate models that may not have enough common data to be stitched properly.
06 After scanning the opposing upper model, scan for the buccal bite.
07 After arrowing forward, set the model axis-a very important step to help assure proper insertion axis as well as more accurate design proposals.
08 Mark the margins (Fig. 3). When marking the pontic margins, use the biocopy of the waxup in the transparent mode to help in placing the margins in the best position for the proposed design.
09 Choose each restoration to copy by outlining the restoration area on the biocopy model (Fig. 4).
10 After outlining the biocopy, the design is stitched to the working model (Fig. 5). An orange peel look indicates a well-stitched biocopy.
11 Individually select each restoration and use the reduce function to reduce each restoration uniformly eight-tenths of a millimeter in order to leave adequate support to stack porcelain. The newly reduced bridge with the transparent biocopy model shows the reduction (Fig. 6).
12 Adjust the connectors to ensure the proper strength needed for a durable zirconia framework (Fig. 7). Figure 8 shows the framework after milling.
13 Smooth the sprue and run a cleaning cycle in the porcelain oven to assure all milling liquid as well as other impurities are burned out to provide a clean framework. When cooled, dip the framework into the coloring solution for 15 minutes to achieve a nice base shading to stack porcelain against (Fig. 9).
14 Set the framework into the muffle of the porcelain oven to completely dry for about 20 minutes to assure it will not crack during sintering.
15 The support bars aren’t cut-off, but are instead left on to stop the possibility of bridge framework warping during sintering. Figure 10 shows the sintered bridge with support bars cut off and ready to stack porcelain.
17 Before stacking to full contour using VM9 porcelain from VITA, it is important to provide a slurry layer of porcelain to add in bonding (Fig. 11).
18 The finished 7-unit bridge is ready to seat (Fig. 12).
Equipped with a full gamut of CAD/CAM components, the inLab system saves time and simplifies the scanning, designing and milling process, resulting in exceptionally accurate and esthetically pleasing end results for complex cases such as a 7-unit lower anterior bridge.
ABOUT THE AUTHOR
Bill Atkission, owner of Bella Vita Dental Designs, Asheville, N.C., has been a crown and bridge technician for nearly 30 years. He attended the Dental Technology Institute in Orange, Calif., and then opened his first sole-proprietorship lab, Bill’s Lab, in 1989. Throughout the years, Atkission has continued to expand his skills to maintain a dental lab with an emphasis on unmatched customer service and offering technology driven products.
This article originally appeared in the March 2014 issue of Dental Lab Products. To learn about more great products, click here to subscribe to DLP's newsletter.